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After more than a decade of waiting and observing patiently, astronomers have found signs that one of the rarest stars known to science is waking up from sleep.
She calls XTE J1810-197 and is part of an exclusive club of strange stars. It is one of four highly magnetic magnets that emit radio waves.
This is at least the case, until a decade ago, when these radio waves were killed. Now it's still moving, and the astronomers have their telescopes ready to record.
It does not sound so exciting, but the magnetars themselves are incredibly strange. They are essentially "dead" stars which, for reasons we do not understand well, have extremely powerful magnetic fields.
To put this in perspective, these incredibly dense collapsed stars can generate magnetic fields of about 1 quadrillion times more powerful than the Earth. So, yes, they are weird.
We currently know 23 magnetars, but the XTE J1810-197 is quite something else. As the magnetars explode into energy, the XTE J1810-197 and only three other stars have detected radio waves.
And then, at the end of 2008, its radio waves suddenly calmed down and remained as such.
Until now.
Since 8 December, researchers from the University of Manchester and the Max Planck Institute for Radio Astronomy have been monitoring a new stream of radio broadcasts from the most unusual cosmic object.
It is interesting to note that the profile of this new radio wave pattern shows some rather significant differences since they were first noticed.
"The pulse variations observed so far from the source have been significantly less dramatic, in the order of a few hours to a few months, compared to 2006," the research team reported.
Among them, tiny ripples of activity on the scale of the millisecond could be caused by small chills in the crust of the star.
The fact is, we still do not know much about magnetars. They seem to form in the same way as your average neutron star, starting with the collapsing nucleus, composed of massive atoms forming a dying star, so that their nuclei are pressed against each other.
At a given moment, the compact body begins to generate magnetic fields of the order of 10-15 gauss. In comparison, a typical fridge magnet is about 50 gauss, which is still 100 times stronger than the magnetic field of our planet on the surface.
What causes such powerful magnetism is a mystery. Most theories suggest that everything could start with the neutron star turning hundreds or even thousands of times a second and turning into a pulsar.
Think of a group of suns crammed into a space the size of a small city whipping with the ferocity of the blades of a helicopter and you can start imagining these monsters.
If this is not intense enough, since their prediction in the late 80s, magnetars have been associated with strange and irregular gamma-ray and X-ray impressions that are repeated in some parts of the sky.
The explanation of these massive explosions of powerful radiation lies in adjustments of the crust filled with star neutrons – the magnetar equivalent of an earthquake – pulling its magnetic field toward new alignments.
The strange thing about XTE J1810-197 is a year after briefly shining in X-rays in 2003, astronomers noticed that he sighed by emitting much smoother radio waves. Early observations showed that it emitted low energy electromagnetic radiation once per revolution, about every five and a half seconds.
It was the first of a handful of magnet radio transmitters that have been discovered since.
This exclusive class of stars blurs the boundaries between these magnetic monsters and garden variety pulsars, their own weaker magnetic fields channeling beams of radiation that shine in the radio waves that sweep the cosmos when they spin. .
Maybe all magnetars produce radio waves in the same way and we see only a few? Perhaps there is something special about the XTE J1810-197 and the other three radio transmitter magnetars?
In pursuing this new study, it is possible that neutron-filled star cracks not only realign its powerful magnetic field, but contribute directly to a range of electromagnetic frequencies including radio waves.
The research is currently available on the pre-review site, arxiv.org, and is therefore expected to generate debate.
Another team of astronomers recently used NASA's Deep Space Network to check XTE J1810-197 and two of its magnetar radio cousins. They also noticed strange variations in radio wave emissions.
Future observations may help dispel speculation about what is behind these impulses and why they come and go as they do.
Now that one of the beasts is awake again, she might still have more to say on the subject.
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